Serial communication between QEMU host and guest

Question

I'm trying to set up a pair of serial ports between my QEMU host (Debian Jessie x86_64) and guest (also Debian Jessie, but on ARM). Everything except the serial port part works.

I'm really new to QEMU so there might be a better way but I've tested the following flags when running QEMU:

-chardev tty,id=mytty,path=/dev/pts/2 (/dev/pts/2 & 3 are up with socat)

-chardev pty,id=mypty QEMU opens a PTY but when I try to read or write from host get permission denied.

In either case I can't find the ports in my guest. /dev/pts is empty and in /dev there are only tty and ttyAMA3. So, my problem is setting up communication in general and I'm especially curious on where the ports are on my guest.

Answer 1

I found a solution to my own question. First the device tree was incomplete so I needed to add 3 additional uart ports. That's the reason I could not find my ports in the guest.

Second, I needed to tell QEMU to use on of the ports as stdio: -append ... console=ttyAMA3 and -serial mon:stdio. Then I'm able to, with -serial pty, link QEMUs ttyAMA* to pts/* on the host.